Quantum / Quantization: It is similar to the difference between Analog to digital domain.
It is a method to express an event, behaviors, actions, objects, matters etc, using smallest element creating / producing such matter instead of expressing it as continues matter. For example, what you may see as solid line, shapes and shades of colors on your computer screen is actually produced by dots lining up next to each other and each dot has discrete value / size even though you may not see it, if the size of each dot is smaller, the resolution is higher. In physics, the smallest quantized elements are elementary particles; in turn it expresses and explains events exist in highest resolution and accuracy to our knowledge and capacity. Quantum physics and quantum mechanics were gradually introduced and developed during 20th century replacing classic physics based on field theory. Field theory is based on our natural perception and observation of space and time continuum.

Event: While we kind of use a word "Event" in our daily life, actually it is a proof that we exist in 4 dimensional realm, we need both "Time" and "Space" to exist and perceived.